The airborne transmission of bacteria and viruses, chiefly respiratory disease organisms is a serious problem in health care. The control of airborne disease transmission has become increasingly important with an increasing number of people traveling in air plains, trains, buses and cars sitting in close proximity to each other.
This coupled with risk of pandemic influenza have created a need for inexpensive, efficient personal respiratory protection system (air purification system). The risk of contracting of air born infections can be reduced by the protection of respiratory organs and eyes from airborne microorganisms along with providing purified air for breathing.
Air purification could be achieved by killing the infectious microorganism by ultraviolet (UV) radiation. Ultraviolet radiation to destroy airborne microorganisms can be used inside of small chamber.
The spread of air borne infections indoors could be controlled by proper ventilation and also by means of personal protection such respirators. Center of Disease Control and Prevention recommends that protection means such a respirators “ . . . should only be used as a “last line of defense” when engineering control systems are not feasible. Engineering control systems, such as adequate ventilation or scrubbing of contaminants should be used to negate the need for respirators”.
The high risk of spread of tuberculosis (TB) infection and other airborne disease during long transcontinental or local flights along with the risk of airborne infections in modern health institutions and correctional institutions indicates however, that the known air purification systems are inadequate in controlling the spread of airborne microorganisms.
There are a number of means which reduce risk of contracting of airborne infection. Among these means are different types of masks and protective gear. The U.S. Pat. Nos. 6,941,949; 6,945,249; 4,488,547 disclosed the examples of face masks.
The disadvantage of protective masks is that they should have proper fit to each wearer. Care should be taken to provide each wearer with a mask that fits properly. This usually can be accomplished only by individual fittings and fit tests. Other disadvantages of face masks include resistance to breathing and need for frequent replacement of air-purifying elements or disposable masks itself.
The masks can provide significant protection against bacteria and spores but have low effectiveness against viruses.
Better degree of protection could provide powered air-purifying respirators. Powered air-purifying respirators provide an airstream to the wearer. U.S. Pat. No. 4,899,740 discloses powered air-purifying respirator system for supplying clean, breathable air to a hood or face mask.
The system can be carried on a waist belt and includes a housing containing air inlet and outlet plenums, and a battery powered, electric motor operated blower connected between the inlet and outlet plenums. PAPR which include hoods and helmets are commonly worn in environments where the air contains contaminants.
Supplied air helmets have a fluid impermeable visor that is located in front of the wearer's face. The visor has a transparent window that allows the wearer to see the surroundings. A face seal is attached to the visor to separate a breathing zone or an interior gas space from the surrounding exterior gas space. U.S. Pat. Nos. 6,014,971, 4,462,399, and 4,280,491 disclose examples of supplied air helmets.
Disadvantages of these PAPR include weight, bulk, complex design, the need for continual maintenance, at least daily replacement of air-purifying elements, and periodic replacement of batteries and blowers. Another disadvantage of masks and protective gear is uncomfortable feeling and sense of isolation from the environment.
There are known other respiratory protection devices for protecting the wearer against inhalation of air-borne particulate matter by creating a high velocity air curtain enclosing the wearer's face. U.S. Pat. Nos. 3,881,478, 7,036,502, and 4,280,491 disclose examples of respiratory protection creating air curtain enclosing wearers face. These devices do not create a sense of isolation. The disadvantages of these devices are their bulk and complex design, and their inability to control viruses. Another shortcoming of the helmet disclosed in U.S. Pat. No. 3,881,478 is the requirement of an air supply from a separate source of clean air. The U.S. Pat. No. 7,036,502 discloses the headset creating a curtain of air across the face. This device has a fan which provides the air supply for the air curtain.
However, the device according to the U.S. Pat. No. 7,036,502 is not convenient for nor adapted to, nor does it address, the matter of providing respiratory protection for the passengers of an airplane or nurses in a hospital or people walking on the streets. According to the U.S. Pat. No. 7,036,502, the headset has a boom with affixed to the boom fan and tubing. According to the U.S. Pat. No. 7,036,502 in addition to the fan and the tubing, the conditioning means are also affixed to the boom. Significant weight of the means of air conditioning makes the moment of force excessive and requires additional means of support affixed to the shoulders or to the neck to keep the headset on the head of the wearer. The boom and an additional means of support, hence, does not lend itself to any kind of “walk-about” portability, which presents operational requirements for the airplanes, hospital or other public places that the device according to the U.S. Pat. No. 7,036,502 had not sought to meet. Further, the device according to the U.S. Pat. No. 7,036,502 cannot be safely used in any situation where people are in close proximity to each other, like an airplane or a hospital or a crowd. The means of directing air flow insures that the breath of the wearer of the device is directed toward the faces of other individuals on the left or the right of the wearer. Any infectious microbes carried by that individual would thus be blown toward the faces of the individuals to the right or the left. The blowing of microbes towards other individuals is counter productive to the idea of protecting individuals from air borne disease.
A variety of air filters have been designed for providing a purified air into supply helmet and further into breathing zone. These filters could used alone or as a sequence of packed bed filter media packets having filter media therein of specifically targeted types that will capture dangerous to human health air pollutants. Examples of air filters for personal air purifiers and helmets are shown in U.S. Pat. Nos. 7,118,608, 6,279,572B1, 6,250,299B1, 6,014,971, 5,125,402, 4,965,887, 4,462,399.
While known personal respiratory protection systems have provided a variety of constructions for establishing a separation between the interior gas space and the surrounding contaminated environment, and for providing a filtered air into the interior space, these known products have not been fashioned to enable a protection from airborne viruses, to improve comfort, and reduce a burden of continual maintenance.
The known products are bulk, have visible solid protective boundaries, which make them uncomfortable for use in an airplane, a hospital, an office or other general environment in which air could be contaminated with infectious microbes.